The present invention relates to turbomachines with extraction systems; and more particularly to a method and a system for reducing the impact on the efficiency of a turbomachine when the extraction system is in operation.
The turbomachines include for example, but not limiting of, a steam turbine, a gas turbine, or the like. The turbomachines may employ an extraction system to remove some of the turbomachine working fluid (steam, or the like) for use in an independent process. The independent process may include, but is not limited to, district heating applications, chemical process, coal gasification, oil heating and atomization, or the like. The extraction system may be required to meet an extraction load requirement of the independent process. The extraction load requirement may include a physical characteristic such as, but not limiting of, pressure, temperature, flow rate of the fluid, and the like.
The extraction load requirement may not be directly related to the turbomachine cycle. The extraction load requirement is generally de-coupled from the variations in the turbomachine load. The turbomachine load may correspond to an electrical and/or a mechanical load. The difference in the extraction load requirement and the turbomachine load may lead to performance and efficiency degradations of the turbomachine. Here, the turbomachine may require attemperation and throttling, to match the extraction load requirement.
There are a few concerns with the currently known methods and systems used for reducing the impact of the efficiency and the performance on a turbomachine operating an extraction system. For example, steam is extracted from a steam turbine at an extraction port that may be located at a fixed high-pressure location; which is typically the steam turbine inlet. As the steam turbine load varies, there may be high performance losses since the steam is not allowed to expand before extraction.
In other methods and systems, a control stage is introduced in order to maintain a constant extraction pressure as steam turbine load varies. Here though, the control stage may also lead to a significant performance loss.
For the foregoing reasons, there is a desire for a method and a system for minimizing the typical performance losses associated with conventional extraction systems. The method and the system should maximize process flexibility, and reduce the impact on the efficiency of the turbomachine operation the extracting system. The method and the system should determine, in near real-time, which of the several distinct extraction location on the turbomachine may be optimum for at a given load requirement.